Practicality and beauty come together in traditional kitchen gardens, where a little forethought and planning can turn the humblest of cabbage patches into a delight for the eye. Briefly tracing the history of horticultural design from ancient Roman times, the Middle Ages and the Renaissance, when formal knot gardens and parterres flourished in Europe, through the lush Victorian carpet bedding, the Gertleys show how vegetable gardeners eager to raise their craft to a more ornamental level can poach traditional elements for their own backyard designs. From the tiniest of garden plots, such as a window box or container, to more expansive spaces, the authors provide instructions for achieving both ""a visual feast and a surprising amount of produce at harvest time."" Everything is here but the seeds--diagrams, plant lists, tips on color harmony and discussions of such dilemmas as dealing with succession planting without spoiling the overall look. If the prose is somewhat utilitarian, the book is commendably thorough, enlivened by vivid photographs that effectively prove the point: visual examples draw on such diverse sources as geometric quilt blocks, family crests, intricate Celtic knots and architectural detail. Elevating the useful to the beautiful has never looked so good, and this guide should help inspire gardeners to bring their vegetable plots out from behind the compost bins and onto center stage. (Mar.)